Because many typical sources of light are small and intense, it has been common in the prior art to provide some means for diffusing, diverting, or otherwise softening or controlling the raw illumination from unobstructed sources. Means for achieving these results include such auxiliary devices as frosted globes for diffusion and a variety of reflecting devices. Further, adjustments to these auxiliary devices often are provided to achieve preferred or more satisfactory conditions of illumination in particular situations. Because many light sources also are hot, materials used in controlling illumination must be selected with due consideration for corrosion and for safety with respect to fire hazards.